Yes — keep them separate. The steppers/controller want a clean, regulated supply (often 12–24 V for the drivers, 5 V/3.3 V logic on the board). The hot wire is a big, variable, noisy resistive load that can dump tens of watts and create voltage sag and electrical noise that upsets stepper drivers and the MCU if they share a rail.
Use one supply for motion electronics and a second dedicated supply for the wire, and tie their grounds at a single point if your heat control needs a common reference (e.g. a MOSFET switched by the controller). This separation also makes it easy to fuse and switch the wire independently for safety.
Use one supply for motion electronics and a second dedicated supply for the wire, and tie their grounds at a single point if your heat control needs a common reference (e.g. a MOSFET switched by the controller). This separation also makes it easy to fuse and switch the wire independently for safety.